1. Field of the Invention
This invention relates to a methotrexate derivative, more specifically to a novel methotrexate derivative available as an antirheumatic agent, psoriasis curing agent and carcinostatic agent.
2. Prior art
Methotrexate has been known as a curing agent of leukemia, and Gubner et al. reported its effectiveness for rheumatoid arthritis (RA) or psoriasis in 1951 and it has been used until then as a curing agent of RA in Europe and the United States. Relatively recently, detailed investigations about method of use and dose have been carried out, and it has been clarified that methotrexate therapy in a low dose develops excellent effectivity with a relatively limited side effects. However, side effects such as hepatopathy or fibroid lung caused by the administration of methotrexate cannot be ignored so that a drug having fewer side effects and increased effectiveness has earnestly been desired.
As methotrexate derivatives to which an alkyl group other than methyl group is introduced at N.sup.10, there have been known for example, the following formula: ##STR2## (J. Med. Chem., 22, p. 862 (1979)) or the formula: ##STR3## (j. Med. Chem. 25, p. 877 (1982)), and the like, however, they did not necessarily show sufficient activity.